The Genetics and Morphology of Some Endosperm Characters in Maize . - P. C. MANGELSDORF The Genetics and Morphology of Some Endosperm Characters in Maize P. C. MANGELSDORF The Bulletins of this Station are mailed free to citizens of Connecticut who apply for them, and to other applicants as far as the editions permit. CONNECTICUT AGRICULTURAL EXPERIMENT STATION OFFICERS AND STAFF as of June, 1926 BOARD OF CONTROL His Excellency, John H. Trumbull, ex-oficio, President. Charles R. Treat, Vice President ................................Orange George A. Hopson, Secretary ............................Mount Carmel Wm. L. Slate, Jr., Treasurer ...............................New Haven Joseph W. Alsop .................................................Avon Elijah Rogers ............................................. Southington Edward C. Schneider ......................................Middletown Francis F. Lincoln ............................................Cheshire STAFF. E. H. JENKINS,PII.D., Director Emeritus. Administration. WM. L. SLATE,JR., B.Sc., Director and Treasurer. MISS L. M. BRAUTLECHT,Bookkeeper and Librarian. V. BERCER,Stenographer and Bookkeeper. E;:: Li ARY E. BRADLEY,Secretary. C. E. GRAHAM,In charge of Buildings and Grounds. Chemistry: E. M. BAILEY,PH.D.. Chemist in Charge. Analvtical C. E. SHEPARD > ~aboratory. OWEN L.J. NOLANFISHER, A,B. W. T. MATHIS FRANKC. SHELDON,Laboratory Assirtant. V. L. CHURCHILL,Sampling Agent. MISS MABELBACON, Stenographer. Biochemical T. B. OSRORNE,PH.D., Chemist in Charge. Laboratory. H. 13. VICKERY,PH.D., Biochemist. MISS HELENC. CANNON.B.S., Dietitian. Botany. G. P. CLINTON,Sc.D., Botanist in Charge. E. M. STODDARD,B.S., Pomologist. MISSFLORENCEA. MCCORMICK, PH.D., Pathologist. WILLISR. HUNTPH.D., Assistant in Botany. A. D. MCDONNELL, General Assistant. MRS. W. W. KELSEY,Secretary. Entomology. W. E. BRITTON,PH.D., Entomologist in Charge; State Entomologist. B. H. WALDEN,B.AGR. M. P. ZAPPE,B.S. ) Aaistant Entomologists. PHILIPGARMAN, P1r.D. ROGERB. FRIEND,B.Sc., Graduate Assistant. JOHNT. ASHWORTH,Deputy in Charge of Gipsy Moth Work. R. C. BOTSPORD,Deputy in Charge of Mosquito Elimination. MISS GRACEA. FOOTE,B.A., Secretary. Forestry. WALTER0. FI~LEY,Forester irt Charge. H. W. HICOCK.M.F Assistant Forester. J. E. RILEY, JR., M.?., 191 charge of Blister Rust Control. MISS PAULINEA. MERCHANT,Stenographer. Plant Breeding. DONALDF. JONES,S.D., Geneticist in Charge. P. C. MANCELSDORP,S.D., Assistant Geneticist. H. R. MURRAY,B.S., Graduate Assistant. Soil Research. M. F. MORGAN,M.S., Investigator. GEORGED. SCARSETH,B.S., Assistant. Tobacco Sub-station PAULJ. ANDERSON,PH.D., Pathologist in Charge. at Windsor. N. T. Nnsoa, PH.D., Plant Physiologist. THE TUTTLE, MOREHOUSE k TAYLOR COYP.4NY TABLE OF CONTENTS PAGE INTRODUCTION.................................................... 513 Definitions ................................................... 514 Aclcnowledgments ............................................ 514 PART I DEFECTIVESEEDS ................................................. Widespread Distribution in Germplasm ....................... Origin by Mutation .......................................... Source of Material .......................................... Simple Mendelian Recessives ................................. Crossing Experiments ........................................ Method of Crossing ......................................... Results of Crosses ........................................... The F2 Generation ........................................... Summary of Crosses ........................................ The Morphology of Defective Seeds .......................... The Cytologial Mechanism of Endosperm Formation .......... Development After Fertilization .............................. Development of Defective Seeds .............................. Regular Development in Early Stages ........................ The Pericarp ................................................ The Nucellus ................................................ The Endosperm .............................................. Starch Grain Formation ..................................... The Aleurone Layer ......................................... The Embryo ................................................. General Aspects ............................................. Physiology of Defective Seeds ................................ Rate of Growth. Final Weight and Germination of Normal Seeds Rate of Growth. Final Weight and Germination of Defective Seeds .................................................... The Influence of Lethal Factors in Heterozygous Condition .... Effect upon the Gametophyte ................................. Linkage Relations ........................................... Linkage Between Sa and de Factors .......................... Linkage of Defectives with Each Other ...................... Linkage of Defectives with Growth Factors .................. A Plant Character for Defective Seeds ...................... Discussion ................................................... Summary .................................................... PART I1 . NON-HEREDITARYDEFECTIVESEWS................................ 564 Parthenocarpic Defectives .................................... 564 Some Conditions Which Influence the Frequency of Partheno- carpic Defectives in Maize ............................. 566 Influence of Age of Silks .................................... 568 Influence of the Age of Pollen .............................. 569 Arrested Develn-ment ........................................ 572 Irregularities in the Fertilization Mechanism ................... 573 Summary .................................................... 578 PART 111 GENETIC FACTORS WHICH INFLUENCETHE TEXTURE05 THE ENDO- SPERM .....................................................579 Brittle Endosperm ........................................... 579 Sugary x Brittle ............................................ 5% Shrunken x Brittle ..........................................582 Brittle Endosperm from Two Varieties ........................ 553 Shrunken Endosperm from Two Sources ..................... 584 Waxy Endosperm in China and America ....................... 584 Constant Variation in the Storage Material of the Endosperm . 585 The Relative Developn~entof Endosperm Characters .......... 586 D~scuss~on...................................................587 Summary .................................................... 589 PART IV PREMATUREGERMINATIONOF MAIZE SEEDSAND GENETICFACTORS WHICHGOVERNDORMANCY ................................ Complementary Factors ...................................... Description Summarized ...................................... Phenotypical and Genetic Differences ........................ Duplicate Factors ............................................ Ratios of 8: I and 41 :I ..................................... Summary of Breedine Behavior ............................. Linkage Relations ............................................ gel x Szc ................................................ gez x su ................................................. ge3 and ges x su ......................................... Apparent Linkage with Endosperm Color Factors ............. Premature Digestion and Pigment Formation ................. The Relation of Premature Germination to Chlorophyll Develop- ment ..................................................... Physiology of Premature Germination ......................... The Effects of Premature Germination on the Growth of the Seed Discuss~on ................................................... Summary ..................................................... CONCLUSION...................................................... LITERATURECITED ................................................ ESPLAXATIONOF PLATES ........................................ The Genetics and Morphology of Some Endosperm Characters in Maize'" When Nawaschin in 1898 discovered the phenomenon of double fertilization in Lilium it was generally believed by botanists that such a peculiar mechanism was confined to this species and per- haps a few closely related ones. Later investigations have shown that it is widely distributed and that the endosperm of angio- sperms, with perhaps a few exceptions, is the product of a sexual fusion, quite apart from that which gives rise to the embryo, and differing from the latter in that one male nucleus combines with two or more female nuclei, while the embryo results from a fusion in which both parents contribute equally. Thus the endosperm of angiosperms is unique in several respects. It resembles its near relative, the embryo, in its sexual origin, but differs from the latter in structure, in capacity for continued development, and in ability to reproduce. This unique sporophyte, if indeed, it may be called a sporophyte, achieves its highest development in the cereals, in which it con- stitutes the part which makes these plants of such great econon~ic importance, and in which it gives evidence of its sexual origin by the expression of the hereditary factors which it receives from its two parents. Mendelian characters which have their expression in the endo- sperm have been found in wheat, rye, barley, rice and maize. They are apparently most numerous in maize and a number of characters which affect the color of the endosperm or aleurone layer and the texture of the endosperm tissue of this species have long been familiar, and have played an important part in the researches leading up